Apparatus and method for preparing composite particulates

ABSTRACT

A method of preparing composite materials by (a) containing particulates to which an adhering material is to be made to adhere, in a rotary body having a bottom surface and a side wall; (b) rotating the rotary body so as to apply centrifugal forces to the particulates in the rotary body; and (c) varying the inclination of the rotary body to an arbitrary inclination angle in the range from an angle at which the bottom surface of the rotary body forms a horizontal surface perpendicular to the direction of gravity to an angle at which the bottom surface forms a vertical surface parallel to the direction of gravity, and supporting the rotary body at the arbitrary inclination angle.

RELATED APPLICATION DATA

This application is a division of U.S. patent application Ser. No.12/395,958, filed Mar. 2, 2009, the entirety of which is incorporatedherein by reference to the extent permitted by law. The presentapplication claims the benefit of priority to Japanese PatentApplication No. 2008-076964 filed in the Japan Patent Office on Mar. 25,2008, the entirety of which is incorporated by reference herein to theextent permitted by law.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method for preparingcomposite particulates by which an adhering material is made to adhereto particulates so as to form composite particulates.

2. Description of the Related Art

As a method for causing an adhering material to adhere to an adhesionsubstrate (a member to which the adhering material is to adhere), therehave been known the PVD (physical vapor deposition) method and the CVD(chemical vapor deposition) method. The CVD method is a method in whichan adhering material (depositing material) is made to adhere to theadhesion substrate (deposition substrate) by a chemical reaction in avapor phase. The PVD method is a method in which an adhering material iscaused to adhere to the adhesion substrate by thermal vapor deposition,sputtering, ion plating or the like.

Of the CVD method and the PVD method, an appropriate one is selected andused, depending on the material constituting the adhesion substrate andthe adhering material. In the cases where the adhesion substrate isparticulates, use is often made of the PVD method which has acomparatively wide range of selection of the adhering material, amongothers, the sputtering method.

The sputtering method is a method in which an anode and a cathode arearranged in a He or Ar gas atmosphere together with an adhesionsubstrate and an adhering material (target) which are located betweenthe anode and the cathode, and a voltage is impressed between theelectrodes, whereby the adhering material is sputtered from the targetand made to adhere to the adhesion substrate.

For the cases where the adhesion substrate is particulates, variousforms of sputtering apparatuses have been proposed in order to achieveuniform adhesion of the adhering material to the whole part of theparticulates.

Examples of the sputtering apparatuses proposed hitherto include asputtering apparatus in which two cylindrical electrodes are coaxiallyarranged on the inner side and the outer side and the outer-sideelectrode is provided with vanes on the inner side thereof (JapanesePatent Laid-Open No. Sho 56-41375), and a sputtering apparatus which isarranged inside a rotary drum for containing a powder along the axialdirection (Japanese Patent Laid-Open No. Hei 5-271921).

In addition to the above, a polygonal barrel sputtering apparatus hasbeen proposed which includes a vacuum vessel polygonal in verticalsectional shape, a rotating mechanism for rotating the vacuum vessel,and a sputtering target disposed inside the vacuum vessel (JapanesePatent Laid-Open No. 2004-250771). In this sputtering apparatus, anadhering material is made to adhere to the surfaces of particulatescontained in the vacuum vessel while rotating the vacuum vessel.

Also, there has been proposed a method of preparing a composite powderin which a tubular rotary stage and a source of an adhering materiallocated at such a position as to be surrounded by the rotary stage areprovided, and the powder is pressed against the inner surface of therotary stage by centrifugal forces generated by rotating the rotarystage (Japanese Patent Laid-Open No. 2008-45197).

SUMMARY OF THE INVENTION

It is known that the method for adhesion (deposition) by sputteringneeds a long treatment time because of the low build-up rate (filmgrowth rate), so that it may be impossible by this method to achieve asufficiently enhanced productivity, depending on the use thereof.

On the other hand, the method by thermal vapor deposition is known topromise a high build-up rate and good productivity. However, unlike thesputtering method, the thermal vapor deposition method may not achieveadhesion (deposition) in a down-sputtering mode in which the adheringmaterial (sputtering target) is disposed on the upper side and theadhering material is sputtered onto the adhesion substrate disposed onthe lower side.

Specifically, in the thermal vapor deposition method, the adhesionsubstrate has to be disposed on the upper side of the vapor source(adhering material) in the manner of facing the vapor source (adheringmaterial) so that the adhering material is evaporated by heating and iscaused to adhere to the adhesion substrate.

In the case where the adhesion substrate is a comparatively largesubstrate such as a substrate of a microcircuit or integrated circuit,it is possible to dispose the substrate in an emission region on theupper side of the vapor source (adhering material) in the manner offacing the vapor source (adhering material), for example, to fix thesubstrate in the desired position by suction.

In the case where the adhesion substrate is particulates, on the otherhand, it is not easy to dispose the plurality of particulates on theupper side of the vapor source (adhering material) in the manner offacing the vapor source (adhering material). Moreover, it is difficultto uniformly vapor-deposit the adhering material to the individual onesof the plurality of particulates stacked on the upper side of andoppositely to the vapor source.

For example, as proposed in Japanese Patent Laid-Open No. 2008-45197,the particulates may be pressed by centrifugal forces against the innersurface of a rotary stage surrounding the vapor source (adheringmaterial). In this case, the particulates are made to traverse the upperside of the vapor source (adhering material) where the emission regionof the vapor source (adhering material) exists, so that the adheringmaterial can be easily vapor-deposited on the particulates.

However, it is difficult to recover the thus prepared compositeparticulates from the inner surface of the cylindrical rotary stage.Thus, the recovery may be low.

Thus, there is a need for an apparatus and a method for preparingcomposite particulates in which particulates placed in a rotary body aregiven centrifugal forces, an adhering material (depositing material) canbe easily made to uniformly adhere to (deposit on) the surfaces of theparticulates, and the recovery of the composite particulates thusprepared through adhesion (deposition) of the adhering material(depositing material) can be enhanced, leading to enhanced productivity.

In order to fulfill the above-mentioned need, the present inventors madeintensive and extensive investigations. As a result of theirinvestigations, it was found out that the above-mentioned need can befulfilled by a system including a mechanism for applying centrifugalforces to particulates contained in a rotary body having a bottomsurface and a side wall, and an inclination varying mechanism forvarying the inclination angle of the rotary body to an arbitrary angleand supporting the rotary body in the thus inclined state.

According to one embodiment of the present invention, there is providedan apparatus for preparing composite particulates, including a rotarybody having a bottom surface and a side wall and operative to containparticulates to which an adhering material is to be made to adhere; acentrifugal machine for rotating the rotary body so as to applycentrifugal forces to the particulates in the rotary body; and aninclination varying device operative to vary the inclination of therotary body to an arbitrary inclination angle in the range from an angleat which the bottom surface of the rotary body forms a horizontalsurface perpendicular to the direction of gravity to an angle at whichthe bottom surface forms a vertical surface parallel to the direction ofgravity, and operative to support the rotary body at the arbitraryinclination angle.

According to another embodiment of the present invention, there isprovided a method of preparing composite materials, including the stepsof containing particulates to which an adhering material is to be madeto adhere, in a rotary body having a bottom surface and a side wall;rotating the rotary body so as to apply centrifugal forces to theparticulates in the rotary body; and varying the inclination of therotary body to an arbitrary inclination angle in the range from an angleat which the bottom surface of the rotary body forms a horizontalsurface perpendicular to the direction of gravity to an angle at whichthe bottom surface forms a vertical surface parallel to the direction ofgravity, and supporting the rotary body at the arbitrary inclinationangle.

In accordance with the embodiments of the present invention, it ispossible to apply centrifugal forces to the particulates contained inthe rotary body, and thereby to easily cause the adhering material toadhere substantially uniformly to the surfaces of the particulates.Besides, it is possible to enhance the recovery of the compositeparticulates thus prepared by adhesion (deposition) of the adheringmaterial (depositing material), and to enhance the productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary preferred embodiment of the apparatusfor preparing composite particulates according to an embodiment of thepresent invention;

FIG. 2 illustrates the condition where centrifugal forces are given tothe particulates, in the apparatus for preparing composite particulatesshown in FIG. 1;

FIG. 3 illustrates the condition where the inclination of the rotarybody is varied, in the apparatus for preparing composite particulatesshown in FIG. 1;

FIGS. 4A to 4D illustrate steps for preparing the compositeparticulates, in the apparatus for preparing composite particulatesshown in FIG. 1;

FIG. 5 illustrates the condition at the time of recovering the compositeparticulates prepared, in the apparatus for preparing compositeparticulates shown in FIG. 1; and

FIGS. 6A to 6C illustrate exemplary preferred embodiments of a stirrerused in the apparatus for preparing composite particulates according tothe present embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, embodiments of the present invention will be described more indetail below referring to the drawings.

FIGS. 1 to 5 illustrate an exemplary preferred embodiment of theapparatus for preparing composite particulates according to anembodiment of the present invention. As shown in FIG. 1, the compositematerial preparing apparatus 10 according to the present embodimentincludes a rotary body 1 for containing particulates 2 to which anadhering material is to be made to deposit, a centrifugal machine 3 forrotating the rotary body 1 so as to apply centrifugal forces to theparticulates 2 contained in the rotary body 1, and an inclinationvarying device 4 for varying the inclination of the rotary body 1 to anarbitrary inclination angle and supporting the rotary body 1 at thearbitrary inclination angle.

The rotary body 1 includes a bottom surface 1 a, a side wall 1 b, and aflange part 1 c provided at one end part of the side wall 1 b so as toface the bottom surface 1 a. Incidentally, the flange part 1 c isprovided in its central area with an opening through which the rotarybody 1 is charged with particulates.

The inclination varying device may be an inclination varying device 4having a turning support member 4 a which supports the rotary body 1 andthe centrifugal machine 3 and an actuator 4 b which turns the turningsupport member 4 a. Incidentally, the actuator 4 b may be, for example,a motor or the like.

In addition, the composite particulate preparing apparatus 10 in thepresent embodiment has a vacuum device (omitted in the drawings) forensuring that the adhesion of the adhering material to the particulates2 in the rotary body 1 can be performed in a vacuum atmosphere.

As shown in FIG. 1, before the start of operation of the compositeparticulate preparing apparatus 10, the rotary body 1 is at rest in thecondition where the bottom surface 1 a forms a horizontal surfaceperpendicular to the direction of gravity. The rotary body 1 is chargedwith particulates 2 to which the adhering material is to be made toadhere.

When charged with the particulates 2, the rotary body 1 is at rest inthe condition where the bottom surface 1 a forms a horizontal surfaceorthogonal to the direction of gravity, it is easy to charge the rotarybody 1 with the particulates 2.

The particulates 2 have a diameter of several micrometers to severalhundreds of micrometers. Examples of the particulates 2 includeparticulates of high-melting-point metals such as iron, and particulatesof carbon.

Next, as shown in FIG. 2, the rotary body 1 is rotated by thecentrifugal machine 3, whereby centrifugal forces are exerted on theparticulates 2 in the rotary body 1, and the particulates 2 are pressedagainst the side wall 1 b of the rotary body 1.

Preferably, the rotating speed of the rotary body 1 is so set that, evenwhen the inclination of the rotary body 1 is varied to such an extentthat the bottom surface 1 a of the rotary body 1 becomes parallel to thevertical direction, the particulates 2 would not drop, in other words, apressing force of not less than that of the gravitational accelerationwould be exerted on every one of the particulates 2. Thus, the rotatingspeed is preferably such that centrifugal forces of not less than 2G areexerted on the particulates 2.

More specifically, the rotating speed of the rotary body 1 is preferablysuch that the rotary body 1 having the bottom surface 1 a with adiameter of about 40 cm and the side wall 1 b with a height of about 10cm is rotated at about 100 rpm. Incidentally, the width of the flangepart 1 c is preferably about 10 cm.

Since the rotary body 1 is provided with the flange part 1 c facing thebottom surface 1 a, the particulates 2 in the rotary body 1 would not bescattered away even when the rotary body 1 is rotated to exert thecentrifugal forces on the particulates 2; thus, during the rotation, theparticulates 2 can be pressed against the side wall 1 b.

Subsequently, as shown in FIG. 3, keeping the condition where thecentrifugal forces are exerted on the particulates 2 in the rotary body1, the turning support member 4 a is turned by the inclination varyingdevice 4 so as to vary the inclination of the rotary body 1 to anarbitrary inclination angle in the range from an angle at which thebottom surface 1 a of the rotary body 1 forms a horizontal surfaceperpendicular to the direction of gravity to an angle at which thebottom surface 1 a forms a vertical surface parallel to the direction ofgravity.

The inclination angle (the angle of the turning support member 4 aagainst the horizontal plane) of the rotary body 1, preferably, is suchan angle that the particulates 2 given the centrifugal forces would notdrop in the direction of gravity.

Specifically, in order to ensure that the adhering material can beeasily vapor-deposited on the particulates 2 pressed against the sidewall 1 b of the rotary body 1, the inclination angle (the angle of theturning support member 4 a against the horizontal plane) of the rotarybody 1 is preferably 45° to 135°, more preferably 80° to 100°,particularly preferably 90°, against the horizontal plane which isperpendicular to the direction of gravity.

The composite particulate preparing apparatus, preferably, includes avapor deposition device in which the adhering material is contained.

In the composite particulate preparing apparatus 10 according to thisembodiment, a vapor deposition device 5 is provided in the rotary body 1supported at such an inclination angle that the bottom surface 1 a isparallel to the vertical direction (namely, at an inclination angle of90° against the horizontal plane).

As shown in FIG. 4A, the vapor deposition device 5 is provided insidethe rotary body 1 supported at such an inclination angle that the bottomsurface 1 a is parallel to the vertical direction (namely, at aninclination angle of 90° against the horizontal plane), and the adheringmaterial 5 a contained in the vapor deposition device 5 is evaporated byheating, to start vapor deposition.

As shown in FIG. 4B, the particulates 2 contained in the rotary body 1and pressed against the side wall 1 b by the centrifugal forces traversethe evaporating direction of the heated adhering material 5 a (theemission region of the adhering material 5 a). Therefore, the adheringmaterial evaporated adheres to the particulates 2 aligned at thesurface, of the plurality of particulates 2 pressed against the sidewall 1 b by the centrifugal forces.

According to the embodiments of the present invention, at the time ofpreparing the composite particulates, the inclination of the rotary bodyis varied to bring the rotary body to such a position where the adheringmaterial evaporated by heating can easily adhere to the particulates,whereby the adhering material is permitted to adhere to the particulatesin the rotary body. Therefore, the efficiency of preparation can beenhanced.

Examples of the adhering material to be made to adhere to theparticulates include low-melting-point elemental metals (such as copperand bismuth), alloys, and organic matters such as paraffins and higheraliphatic acids.

The composite particulate preparing apparatus 10 in this embodiment hasa stirrer for stirring the particulates 2 pressed against the side wall1 b of the rotary body 1 by the centrifugal forces.

The stirrer may be a comb-shaped stirring member 6 in which, as shown inFIGS. 4A to 4D, a support member 6 a parallel to the side wall 1 b ofthe rotary body 1 is provided with a plurality of bar-like members 6 bprojecting in the same direction.

As shown in FIG. 4C, in operation of the stirring member 6, thecombtooth-shaped bar-like members 6 b are inserted between the pluralityof particulates 2 pressed against the side wall 1 b of the rotary body 1and are brought into line contact with the plurality of particulates 2,whereby the particulates 2 on the surface side and the particulates 2 onthe side of the side wall 2 b are stirred. With the particulates 2stirred sufficiently by the stirring member 6, the particulates on thesurface side and the particulates on the side of the side wall 2 b arereplaced by one another, whereby the adhering material can be made tosubstantially uniformly adhere to the surfaces of the particulates,resulting in preparation of the composite particulates.

As shown in FIGS. 4A to 4D, the composite particulate preparingapparatus 10 in this embodiment, preferably, is provided with a filmthickness monitor 7 for measuring the film thickness of the adheringmaterial having adhered to the particulates 2.

As shown in FIG. 4D, the film thickness of the adhering material havingadhered to the particulates 2 is measured by the film thickness monitor7, so as to prepare the composite particles 20 through adhesion of theadhering material in an arbitrary and substantially uniform filmthickness.

Incidentally, the measured value of the film thickness of the adheringmaterial as measured by the film thickness monitor 7 may be differentfrom the actually measured value of the film thickness of the adheringmaterial having actually adhered to the particulates 2, depending on thevapor deposition conditions or the like. The ratio of the value measuredby the film thickness monitor 7 and the actually measured value ispreliminarily calculated, and the adhering material is vapor-depositedon the particulates 2 in an optimal film thickness by way ofproportional calculation.

Thereafter, as shown in FIG. 5, the turning support member 4 a is turnedby the inclination varying device 4 to vary the inclination angle of therotary body 1 from the angle at which the bottom surface 1 a of therotary body 1 forms a vertical surface parallel to the direction ofgravity to the angle at which the bottom surface 1 a forms a horizontalsurface perpendicular to the direction of gravity, and the centrifugalmachine 3 is stopped.

With the centrifugal machine 3 stopped, the composite particulates 20having been pressed against the side wall 1 b of the rotary body 1 bythe centrifugal forces drop in the direction of gravity, and the thusdropped composite particulates 20 are recovered.

According to the embodiments of the present invention, at the time ofrecovering the composite particulates, the inclination angle of therotary body can be varied so that the bottom surface of the rotary bodyagain forms the horizontal surface perpendicular to the direction ofgravity, and, therefore, the composite particulates prepared can berecovered at good efficiency.

When the strength with which the particulates 2 contained in the rotarybody 1 is stirred is not appropriate, it is difficult to cause theadhering material to adhere to the surfaces of the particulates 2 in asubstantially uniform film thickness.

Specifically, in the case where the amount of the particulates 2contained in the rotary body 1 is small, if the strength of stirring bythe stirrer is high, the particulates 2 pressed against the side wall 1b of the rotary body 1 would easily come out of position. Therefore, itis difficult to prepare the composite particulates 20. On the otherhand, in the case where the amount of the particulates 2 contained inthe rotary body 1 is large, if the strength of stirring by the stirreris low, the adhering material would adhere to only the particulates 2present on the surface side, of the plurality of particulates 2 stackedto an arbitrary thickness from the side wall 1 b. Therefore, it isdifficult to cause the adhering material to adhere to the plurality ofparticulates 2 substantially uniformly, thereby preparing the compositeparticulates 20 desired.

The rotating speed for producing the centrifugal forces with which topress the particulates 2 against the side wall 1 b of the rotary body 1is substantially constant, irrespectively of the amount of theparticulates 2 contained in the rotary body 1. Therefore, it ispreferable to change the form of the stirrer according to the amount ofthe particulates 2 contained in the rotary body 1, the particle diameterof the particulates 2, the fluidity of the particulates 2, etc.

FIGS. 6A to 6C illustrate schematic configurations of various forms ofstirrers.

As shown in FIG. 6A, in the case where the amount of the particulates 2contained in the rotary body 1 is large, i.e., where the layer of theparticulates 2 to be pressed against the side wall 1 b of the rotarybody 1 by centrifugal forces is thick, a stirring member 8 in which asurface member 8 a for surface contact with the plurality ofparticulates 2 is attached to a support member 8 b is preferably used.Since the rotary body 1 is rotated at such a speed as to exertcentrifugal forces on the particulates 2, the surface contact of thesurface member 8 a with the particulates 2 in rotation ensures that theparticulates 2 on the surface side and the particulates 2 on the side ofthe side wall 1 b of the rotary body 1 are stirred while the individualparticulates 2 themselves are rotating.

Incidentally, the expression “the case where the amount of theparticulates 2 is large” means the case where the layer of theparticulates 2 pressed by the centrifugal force has a thickness of about5 to 8 cm, in a rotary body 1 having a bottom surface 1 a with adiameter of about 40 cm, a side wall 1 b with a height of about 10 cm,and a flange part 1 c with a width of about 10 cm.

As shown in FIG. 6B, in the case where the amount of the particulates 2contained in the rotary body 1 is somewhat small, i.e., where the layerof the particulates 2 pressed against the side wall 1 b of the rotarybody 1 is somewhat thin, a stirring member 9 in which a plurality ofbar-like members 9 a for line contact with the plurality of particulates2 are attached to a support member 9 b in a combtooth-like form ispreferably used. With the bar-like members 9 a inserted between theplurality of particulates 2 and with the support member 9 b reciprocatedin the direction parallel to the rotational axis of the rotary body 1,the plurality of particulates 2 are entirely stirred uniformly.

Incidentally, the expression “the case where the amount of theparticulates 2 is somewhat small” means the case where the layer of theparticulates 2 pressed by the centrifugal forces has a thickness ofabout 3 to 4 cm, in a rotary body 1 having a bottom surface 1 a with adiameter of about 40 cm, a side wall 1 b with a height of about 10 cm,and a flange part 1 c with a width of about 10 cm.

As shown in FIG. 6C, in the case where the amount of the particulates 2contained in the rotary body 1 is small, i.e., where the layer of theparticulates 2 pressed against the side wall 1 b of the rotary body 1 isthin, a stirring member 11 in which a plurality of bar-like members 11 afor point contact with the plurality of particulates 2 are radiallyprojected from a support member 11 b is preferably used. With the tipsof the bar-like members 11 a put into point contact with theparticulates 2 the amount of which is small and the moment of inertia ofwhich is small, by the rotation of the rotary body 1, the plurality ofparticulates 2 are entirely stirred uniformly.

Incidentally, the expression “the case where the amount of theparticulates 2 is small” means the case where the layer of theparticulates 2 pressed by the centrifugal forces has a thickness ofabout 1 to 2 cm, in a rotary body 1 having a bottom surface 1 a with adiameter of about 40 cm, a side wall 1 b with a height of about 10 cm,and a flange part 1 c with a width of about 10 cm.

The method of preparing composite particulates according to anembodiment of the present invention includes the steps of containingparticulates to which an adhering material is to be made to adhere, in arotary body having a bottom surface and a side wall; rotating the rotarybody so as to apply centrifugal forces to the particulates in the rotarybody; and varying the inclination of the rotary body to an arbitraryinclination angle in the range from an angle at which the bottom surfaceof the rotary body forms a horizontal surface perpendicular to thedirection of gravity to an angle at which the bottom surface forms avertical surface parallel to the direction of gravity, and supportingthe rotary body at the arbitrary inclination angle.

The method of preparing composite particulates according to thisembodiment, preferably, includes a step of vapor-depositing the adheringmaterial to the particulates given the centrifugal forces. In addition,the method preferably includes a step of stirring the particulates giventhe centrifugal forces.

According to this embodiment of the present invention, in each of thestep of charging the rotary body with the particulates, the step ofadhesion of the adhering material to the particulates, and the step ofrecovering the composite particulates, the inclination of the rotarybody for containing the particulates therein can be varied to an angularposition at which the relevant step can be easily carried out.Therefore, the adhering material can be adhered to the surfaces of theparticulates substantially uniformly, the recovery of the compositeparticulates can be enhanced, and the productivity can be enhanced.

EXAMPLE

Now, the embodiments of the present invention will be described, basedon a non-limitative example thereof.

Example

Using the composite particulate preparing apparatus 10 as shown in FIGS.1 to 5, an adhering material (bismuth) was vapor-deposited on ironparticulates having a specific gravity of about 2 and a mean particlediameter of 5 μm.

First, the rotary body 1 having a bottom surface 1 a with a diameter ofabout 40 cm, a side wall 1 b with a height of about 10 cm, and a flangepart 1 c with a width of about 10 cm, of the composite particulatepreparing apparatus 10, was set in such an angular position that thebottom surface 1 a of the rotary body 1 forms a horizontal surfaceperpendicular to the direction of gravity. In this condition, the rotarybody 1 was charged with iron particulates in such an amount that thelayer of the particulates 2 pressed by centrifugal forces would have athickness of about 3 to 4 cm.

Next, the rotary body 1 was rotated at 100 rpm to exert the centrifugalforces on the iron particulates, thereby pressing the iron particulatesagainst the side wall 1 b of the rotary body 1. Under this condition,the inclination of the rotary body 1 was varied by the inclinationvarying device 4 to an angular position at which the bottom surface 1 aof the rotary body 1 formed a vertical surface parallel to the directionof gravity (an inclination angle of 90°. In this condition, while theiron particulates in the rotary body 1 were stirred by the stirringmember 6 and the film thickness was measured by the film thicknessmonitor 7, bismuth was vapor-deposited on the iron particulates, toprepare composite particulates.

Thereafter, the inclination varying device 4 was again operated to varythe inclination of the rotary body 1 from an angular position at whichthe bottom surface 1 a of the rotary body 1 formed a vertical surfaceparallel to the direction of gravity to an angular position at which thebottom surface 1 a formed a horizontal surface perpendicular to thedirection of gravity, the centrifugal machine 3 was stopped, and thecomposite particulates 20 were recovered. The recovery was 98%.

Comparative Example

Composite particulates were prepared in the same manner as in Exampleabove, except that a rotary body so supported that the bottom surface ofthe rotary body forms a vertical surface parallel to the direction ofgravity was used and the inclination angle of the rotary body was keptunchanged. The recovery of the composite particulates was 70 to 90%.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factor in so far as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A method of preparing composite materials,comprising the steps of: placing particulates and an adhering materialin a rotary body having a planar bottom surface, a side wall extendingfrom said bottom surface, and an inwardly extending flange at an end ofthe side wall away from the bottom surface, the flange leaving throughwhich the particulates can be fed into the rotary body; rotating saidrotary body so as to apply centrifugal forces of about 2G or more tosaid particulates in said rotary body; while the centrifugal forces areapplied to said particulates, varying the inclination of said rotarybody from an arbitrary inclination angle at which said bottom surface ofsaid rotary body forms a horizontal surface perpendicular to thedirection of gravity to an arbitrary inclination angle at which saidbottom surface forms a vertical surface parallel to the direction ofgravity, and supporting said rotary body at said arbitrary inclinationangles; and also while the centrifugal forces are applied to saidparticulates, vapor depositing said adhering material onto saidparticulates.
 2. The method of preparing composite particulates as setforth in claim 1, further comprising a step of causing said adheringmaterial to adhere to said particulates by means of the centrifugalforces applied to said adhering material and said particulates.
 3. Themethod of preparing composite particulates as set forth in claim 1,further comprising a step of stirring said particulates by means of thecentrifugal forces applied to said particulates.
 4. The method ofpreparing composite particulates as set forth in claim 1, comprising thefurther steps of: supporting the rotary body at a first end of an arm;rotating said rotary body at said first end of said arm; and varying theinclination of said rotary body by pivoting said arm about a second endof said arm.
 5. The method of claim 1, wherein the particulates aresubjected to vacuum pressure in the rotary body while being subjected tocentrifugal forces.